A pre-op (preoperative) evaluation is a medical appointment that happens before your surgery to make sure you’re safe to undergo the procedure and anesthesia. It typically includes a detailed review of your medical history, a physical exam, and possibly blood work or heart testing depending on your health and the complexity of the surgery. Most pre-op visits take place within 30 days of your procedure, though the results must be updated within 48 hours of surgery day if anything has changed.
Medical History Review
The medical history is considered the single most important part of the preoperative evaluation. Your care team will ask about your current and past health conditions, previous surgeries, family medical history, and lifestyle factors like tobacco use, alcohol consumption, and recreational drug use. They’ll also want a complete list of every medication you take, including over-the-counter drugs, vitamins, and herbal supplements.
Expect specific questions about your experience with anesthesia. If you’ve ever had a bad reaction to being put under, or if anyone in your family has, that information directly affects how your anesthesia team plans your care. You’ll also be asked about drug allergies and any unusual responses you’ve had to medications in the past.
Physical Examination
The physical exam focuses on your heart, lungs, and overall fitness for surgery. Your provider is looking for anything that could increase your risk of complications during or after the procedure. A key part of this assessment is your functional capacity: how much physical activity you can handle in daily life. If you can walk up one or two flights of stairs without chest pain or significant breathlessness, that’s generally a reassuring sign of low cardiac risk.
The anesthesia team will also evaluate your airway, checking factors like how wide you can open your mouth, the size and shape of your jaw, and the visibility of structures in the back of your throat. This helps them plan the safest approach for placing a breathing tube if general anesthesia is required.
Blood Tests and Other Screenings
Not everyone gets the same tests. Current guidelines recommend ordering lab work based on your individual health, the medications you take, and the type of surgery you’re having, not as a blanket routine. A complete blood count is one of the most common pre-op tests, used to check for anemia, clotting issues, and signs of infection. You may also have blood drawn to check your blood sugar, kidney function, and electrolyte levels.
Heart testing follows a similar “only if needed” approach. For most people, even those with known heart disease, a preoperative electrocardiogram (EKG) isn’t necessary before low-risk surgeries. It becomes more relevant for older or inactive patients with heart conditions who are facing major surgery. If an EKG shows something concerning, your doctor may follow up with additional testing, such as an exercise stress test that monitors your heart while you walk on a treadmill. A chest X-ray may be ordered if there are concerns about your lung function.
Risk Classification
During your pre-op, your anesthesia provider assigns you a risk score on a scale of 1 to 6. A Class 1 patient is completely healthy with no medical conditions. Class 2 means you have a mild condition like well-controlled high blood pressure. Class 3 indicates a more serious issue, such as significant obesity or poorly managed diabetes. Classes 4 and 5 are reserved for patients with life-threatening conditions, and Class 6 applies only to brain-dead organ donors. This score helps the surgical and anesthesia teams calibrate their approach and anticipate potential problems.
Medications You May Need to Stop
One of the most practical things that happens at a pre-op is a medication review, specifically identifying drugs and supplements that need to be paused before surgery because they increase bleeding risk or interact with anesthesia.
- Blood thinners: Medications like clopidogrel need to be stopped at least 5 days before surgery, while prasugrel requires 7 days. Your surgeon and cardiologist will coordinate on the exact plan if you take these for a heart condition.
- Aspirin: Typically stopped 7 days before non-heart surgery, though patients with coronary stents usually stay on low-dose aspirin unless bleeding risk is too high.
- Over-the-counter pain relievers: Ibuprofen (Advil, Motrin) should be stopped at least 1 day before surgery, while naproxen (Aleve) needs 4 days.
- Vitamins, supplements, and herbal products: All should be discontinued 7 days before surgery. Many common supplements, including fish oil and certain herbal remedies, can thin your blood in ways that aren’t always obvious.
You’ll receive specific instructions about which of your regular medications to continue taking on the morning of surgery (often with a small sip of water) and which to hold.
Fasting Instructions
If your surgery involves general anesthesia, sedation, or regional anesthesia, you’ll be given fasting guidelines. The American Society of Anesthesiologists recommends stopping clear liquids (water, black coffee, apple juice) at least 2 hours before your procedure. A light meal or non-dairy milk must be finished at least 6 hours beforehand. Heavier foods like fried items, fatty meals, or meat may require 8 or more hours of fasting. These rules exist to keep your stomach empty and reduce the risk of vomiting and inhaling stomach contents while you’re under anesthesia.
Consent and Discharge Planning
You’ll sign informed consent documents confirming that your surgeon has explained the procedure, its risks, potential complications, and available alternatives. Take this step seriously. It’s your opportunity to ask questions about anything you don’t fully understand, including what recovery looks like and what could go wrong.
For outpatient or same-day surgeries, the pre-op team will also assess your discharge plan. They need to know that you have a responsible adult who can drive you home after anesthesia, and that your home situation supports recovery. This means evaluating whether you can manage basic daily activities like getting to the bathroom, preparing food, and moving around safely. If you live alone or have mobility concerns, this is the time to flag that so arrangements can be made, whether that’s lining up extra help at home or planning for a short stay in a recovery facility.